Titanium dioxide pigments have many known applications, particularly for uses in coatings, paper, and plastics. When incorporated into polymers for plastics applications, the titanium dioxide pigment may act as a filler, or it may also be used to impart improved chemical and physical attributes to polymer matrices, including improved thermal stability, decreased chemical activity, and improved lacing resistance. Lacing resistance is particularly important in extruded polymer film applications.
Although untreated titanium dioxide may be useful in polymer applications, it has been found beneficial to treat the pigments prior to use. Pigments may be treated in different ways, including the addition of surface treatments. For instance, U.S. Pat. No. 6,646,037 teaches the treatment of pigments with organosulfonic acid compounds to impart improved physical and chemical qualities to polymeric matrices. U.S. Pat. No. 6,765,041 teaches treating pigments with organo-acid phosphates. In addition, U.S. Pat. No. 5,837,049 teaches treating pigments with an alkylphosphonic acid or ester.
Despite the variety of surface treatments, for various reasons, including cost and desired properties, no known surface treatments are ideal for all applications. Thus, there is always a need to develop new and better treatments for pigments.